This is also not the case in many real life examples of trans friends who readily are outgoing and make friends I see and know. I believe they were using that quote from something above that was mentioned as being a quote from autism spectrum disorder, and they were using it as a parallel. It's also not the case in many autistic friends, though. I know many close friends on the spectrum that are loud, outgoing and make friends very readily.
They usually don't quite look like their gender of choice landing them in somewhat of an uncanny valley. Me or you will have an instinctive negative reaction to them which will then have to be overcome. Of course that doesn't mean they never make any friends. But that is not what is being said. What is being said is they will have more unsuccessful attempts than the average person.
> They usually don't quite look like their gender of choice
This is confirmation bias. You notice people who don't look like you think they should look. You then think those people are trans, and when you check a few it turns out they are trans. You've confirmed your bias, and now you think it's true.
What you haven't taken into account is all the people who don't fit this pattern: athletic black women who were born female and identify as female but who are assumed to be transwomen (see all the conspiracy theories around Michelle Obama or the Williams sisters), or the people who do pass well that you're just not aware of.